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11.
It is shown that the countably infinite dimensional pointed vector space (the vector space equipped with a constant) over a finite field has infinitely many first order definable reducts. This implies that the countable homogeneous Boolean-algebra has infinitely many reducts. 相似文献
12.
Ladislaus Erdey und Andreas Bodor 《Fresenius' Journal of Analytical Chemistry》1951,133(1):265-274
Zusammenfassung Die beschriebene direkte Chloratbestimmung gründet sich auf die katalytische Wirkung der selenigen Säure auf die Ascorbinsäure-Chloratreaktion. Der Endpunkt der in stark saurer Lösung durchgeführten Titration wird durch das sich ausscheidende Selen angezeigt. Die Anwesenheit zweiwertiger Mangansalze begünstigt das Wahrnehmen des Endpunktes, da Mangan(II)-Ionen die Reduktion der selenigen Säure durch Ascorbinsäure verzögern. Die Titration ist am besten bei 60° C durchzuführen. Es werden praktische Anwendungsmöglichkeiten des Titrationsverfahrens angegeben.Wir danken Frau Helene Buzás für ihre wertvolle Mithilfe bei Ausführung unserer Versuche. 相似文献
13.
Zsanett Bodor Zoltan Kovacs Csilla Benedek Gza Hitka Hermann Behling 《Molecules (Basel, Switzerland)》2021,26(23)
The objective of the study was to check the authenticity of Hungarian honey using physicochemical analysis, near infrared spectroscopy, and melissopalynology. In the study, 87 samples from different botanical origins such as acacia, bastard indigo, rape, sunflower, linden, honeydew, milkweed, and sweet chestnut were collected. The samples were analyzed by physicochemical methods (pH, electrical conductivity, and moisture), melissopalynology (300 pollen grains counted), and near infrared spectroscopy (NIRS:740–1700 nm). During the evaluation of the data PCA-LDA models were built for the classification of different botanical and geographical origins, using the methods separately, and in combination (low-level data fusion). PC number optimization and external validation were applied for all the models. Botanical origin classification models were >90% and >55% accurate in the case of the pollen and NIR methods. Improved results were obtained with the combination of the physicochemical, melissopalynology, and NIRS techniques, which provided >99% and >81% accuracy for botanical and geographical origin classification models, respectively. The combination of these methods could be a promising tool for origin identification of honey. 相似文献
14.
For a spin-2, free quantum field there exists a Lagrange formulation leading to the Klein-Gordon equation, and the subsidiary conditions are added separately. This reproduces the usual interpretation of the field by spin-2 particles. If subsidiary conditions are not introduced, the symmetrical tensor field of rank two is decomposed into its components of spin-2,1,0 and only the spin-2,0 components define a physical theory. Various Lagrange formulations become inequivalent when a tensor interaction is introduced because the current can fix the trace and/or the divergence of the field. 相似文献
15.
MNDO and AMI studies were performed to investigate the degenerate hydride transfer reaction between 1-methyl-l,4-dihydronicotinamide and the 1-methylnicotinamide cation, a model system for a novel brain-targeted delivery system and for the NAD+ (ai) NADH interconversion. Four initial approach vectors were selected. These involved an endo orientation in which the carbamoyl groups are
with respect to one another (cis HS-
), an endo orientation with the carbamoyl groups
(cis HS-si), an exo configuration with the carbamoyl groups syn (trans HS-
) and an exo configuration with the carbamoyl groups
(trans HS-
). The cis HS-
approach generated the transition state with the lowest energy. The optimized structure indicated that a linear hydride transfer occurred. A more detailed study examined the cis HS-
approach from a 100A separation to the transition state. The data indicated the formation of an intermediate induced dipole-charge complex which altered the trajectory of the two species. Closer approach yielded the transition state. The energy of activation for this reaction was calculated to be 30.7 kcal/mol using the MNDO approximation and 9.3 kcal/mol usihg the AMI method. Finally, while the linear transition state was found to be the most stable conformation, bending of the C-H-C bond by ± 30° only modestly increased (3–4 kcal/mol) the energy of the system. 相似文献
16.
The use of capillary zone electrophoresis (CZE) on-line coupled with isotachophoresis (ITP) sample pretreatment (ITP-CZE) on a poly(methylmethacrylate) chip, provided with two separation channels in the column-coupling (CC) arrangement and on-column conductivity detection sensors, to the determination of bromate in drinking water was investigated. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the ITP-CZE separations. A high sample load capacity, linked with the use of ITP in this combination, made possible loading of the samples by a 9.2 microL sample injection channel of the chip. In addition, bromate was concentrated by a factor of 10(3) or more in the ITP stage of the separation and, therefore, its transfer to the CZE stage characterized negligible injection dispersion. This, along with a favorable electric conductivity of the carrier electrolyte solution, contributed to a 20 nmol/L (2.5 ppb) limit of detection for bromate in the CZE stage. Sample cleanup, integrated into the ITP stage, effectively complemented such a detection sensitivity and bromate could be quantified in drinking water matrices when its concentration was 80 nmol/L (10 ppb) or slightly less while the concentrations of anionic macroconstituent (chloride, sulfate, nitrate) in the loaded sample corresponding to a 2 mmol/L (70 ppm) concentration of chloride were still tolerable. The samples containing macroconstituents at higher concentrations required appropriate dilutions and, consequently, bromate in these samples could be directly determined only at proportionally higher concentrations. 相似文献
17.
Ladislaus Erdey Andreas Bodor und Helene Buzás 《Fresenius' Journal of Analytical Chemistry》1952,134(6):412-419
Zusammenfassung In schwach saurer (0,2–0,5 n)-Lösung sind Bromate in Anwesenheit von seleniger Säure als Katalysator mit Ascorbinsäure bestimmbar. Man fügt zur Lösung HgCl2, welches die entstehenden Bromide in einer wenig dissoziierten Komplexform bindet und den Endpunkt der Titration durch Kalomelausscheidung kenntlich macht. Setzt man MnSO4 zur Lösung und beendet die Titration langsam, so vermeidet man eine Übertitration. Die Bestimmung ist bei Zimmertemperatur durchzuführen. Die störende Wirkung fremder Salze wurde untersucht. 相似文献
18.
19.
A convenient method is described for the preparation of phosphate diester monoanions. The method uses readily available starting materials and does not require the isolation and handling of highly toxic phosphate triesters. The title compounds are useful as models of aged (poisoned) acetyl cholinesterase systems. 相似文献
20.
Kanianskya D Masár M Danková M Bodor R Rákocyová R Pilná M Jöhnck M Stanislawski B Kajan S 《Journal of chromatography. A》2004,1051(1-2):33-42
This feasibility study deals with column switching in zone electrophoresis (ZE) separations on a column coupling (CC) chip. The column switching implemented into the ZE separations an on-chip sample clean up applicable for both the multicomponent and high salinity samples. In addition, complemented by different separation mechanisms in the coupled columns (channels), it provided benefits of two-dimensional separations. Properly timed column switching gave column-to-column transfers of the analytes, characterized by 99-102% recoveries, delivered to the second separation stage on the chip the analyte containing fractions contaminated only with minimum amounts of the matrix constituents. A diffusion driven transport of the matrix constituents to the second channel of the chip (due to direct contacts of the electrolyte solutions in the bifurcation region), representing 0.1-0.2% of the loaded sample constituents, was found to accompany the sample clean up performed on the CC chip. This source of potential disturbances to the separation in the second channel, however, is not detectable in a majority of practical situations. With respect to a 900 nl volume of the sample channel on the CC chip, the electric field and isotachophoresis (ITP) stackings were employed to minimize the injection dispersion in the separations and concentrate the analytes. Here, the column switching, removing a major part of the stacker from the separation system, provided a tool effective in a control of the destacking of analytes. Highly reproducible ZE separations as attained in this work also for the chip-to-chip and equipment-to-equipment frames can be ascribed, at least in part, to suppressions of electroosmotic and hydrodynamic flows of the solutions in which the separations were performed. 相似文献